This invention relates to a padlock and key assembly, and more particularly to one which has transversely movable tumbler units and vertically movable tumbler units.
The improvement of this invention is directed to a conventional pin-tumbler padlock of the type shown in FIG. 1. This conventional padlock includes a body 11, a lock core or key plug 12 mounted rotatably within the body 11, a shackle 13 having long and short legs, and locking bolt members 14 and 15. Four spring biased tumbler units 16 pass through the body 11 and key plug 12 for preventing the rotation of the key plug 12 relative to the body 11. The key plug 12 has a key hole 121 which is shaped to mate with a flat key 17 (see FIG. 2) or a cylindrical key 18 (see FIG. 3). When mating the key hole 121 with the flat key 17, the flat key 17 is first inserted into the key hole 121 so that the tumbler units 16 are moved to release the key plug 12 from the body 11, and then the flat key 17 together with the key plug 12 are rotated. Each of the locking bolt members 14 and 15 has an inner L-shaped arm 141, 151, and an outer tapered arm 142, 152. The tapered arms 142 and 152 are respectively inserted into two notches 131 and 132 of the shackle 13 for retaining the short leg of the shackle 13 on the body 11. Upon rotation of the key plug 12, the upper end tenon 123 of the key plug 12 pushes the L-shaped arms 141 and 151 inward so that the tapered arms 142 and 152 separate from the notches 131 and 132 respectively, as shown in FIG. 4. In response to the separation of the bolt members 14 and 15 from the shackle 13, a spring pushes the shackle 13 upward so that the short leg of the shackle 13 separates from the body 11, thereby opening the padlock. Because the flat key 17 is thin and the opening of the key hole 121 is small, it is difficult to mate the key hole 121 with the flat key 17 in poor lighting. When the key hole 121 is mated with the cylindrical key 18, the cylindrical key 18 is inserted into the key hole 121 to engage an interior transverse pin 122 fixed in the key plug 12 with the end slot 181 of the cylindrical key 18. This engagement of the pin 122 with the slot 181 permits the synchronous rotation of the cylindrical key 18 and the key plug 12. The cylindrical key 18 is then rotated in the same manner as that of the flat key 17 to open the padlock. Although it is easy to mate the key hole 121 with the cylindrical key 18, the transversely movable tumbler units 16 are not sufficient to ensure the safety of the padlock.